Traffic load is typically not evenly distributed over the sensor nodes in a Wireless Sensor Network (WSN). Understanding the traffic load distribution can guide the network-wide energy allocation, the design of routing algorithms, and the optimization of the node deployment in WSNs. This paper considers a dense WSN with nodes uniformly distributed in a disk sensing area, where the expected traffic load distribution over the sensor nodes as a function of their distance from the sink has been derived. Further, the effects of the network scale and routing strategy on traffic load distribution are also investigated.